like the thread title says: I'm located in Southern NH, allegedly we have 4 seasons although I'm having my doubts about the veracity of that (loonnng winter)

I have an attached 2 car garage with a single door. I wish to insulate it prior to putting up pegboard around the exterior walls. There is soffit ventilation and a ridge vent.

Edit I should mention that the south wall doesn't have a soffit. The west and east walls do. The south wall goes up 8' to the header that parallels the trusses. I plan to put pegboard to the bottom of the header. Question: Will the pegboard suffice for ventilation on that wall? /Edit

Can I use kraft backed fiberglass insulation on the walls and the roof? Will I need a plastic vapor barrier? I do not plan to panel the roof. There is no room above the garage. Could I use lattice to hold the insulation on the roof joists?